Digital printing, including inkjet, is a method of reproducing an image or data onto a medium directly from a computer, typically on conventional substrates. When the ink is applied onto the media, it should stay in a tight, symmetrical dot; otherwise the dots of the ink will begin to penetrate into the receiving media, feather, or spread out in an irregular fashion to cover a slightly larger area than the digital printer designer intended (dot gains). The result is an image or data that appears to have low color intensity, fuzziness, especially at the edges of objects and text, etc. (color bleeding or color to color bleeding).
EP 1 924 658 to E.I. Du Pont de Nemours describes an aqueous vehicle (ink) having dispersed therein titanium dioxide pigment dispersed with a polymeric dispersant and a crosslinked polyurethane binder additive (different from the polymeric dispersant). The white ink was deemed especially useful for printing images on non-white textiles.
US 2008/0092309 A1 to E.I. Du Pont de Nemours describe an aqueous inkjet printing pretreatment comprising a nonionic latex polymer and a multivalent cationic salt.
US 2007/0103528 to Kornit relates to an ink for digitally printing to produce high-quality and durable abrasion-fast image which will not deteriorate in washes or be harsh to the touch and brittle.
EP 1 356 155 to Kimberly-Clark Worldwide, Inc. relates to a cationic polymer coating formulation for ink jet printing used in conjunction with imbibing solutions. The imbibing solutions can be urea (for acid dye-based ink) or ammonium salts such as ammonium oxalate and ammonium tartrate. In one embodiment, the formulation includes 5-95% cationic polymers or copolymers and from about 5-20% fabric softeners. The cationic polymers are shown in FIGS. 1A-1C of the reference and appear to be free radically polymerized polymers such as from diallyl ammonium monomers.
EP 1 240 383 to Kimberly Clark Worldwide, Inc. relates to coating formulation improvements including imbibing solutions for treating substrates such as cationic polymers or copolymers and fabric softeners. It also describes polymeric latex binders' ability to increase washfastness.
U.S. Pat. No. 6,291,023 teaches a coating agent comprising an agent selected from one of a) azetidinium polymer, b) guanidine polymer, c) a mixture of azetidinium polymer and a guanidine polymer, and d) a copolymer of azetidinium monomer and a guanidine monomer. The coating is used on textiles to provide high quality printed images when printed with reactive dye.
WO92/07124 discloses a treatment for fibres using polymers carrying imidazoline and azetidinium groups. WO98/29530 discloses laundry detergent compositions with polyamide-polyamines to provide appearance benefits. Epichlorohydrin reaction products with adipic acid-diethylenetriamine are disclosed in the abstract. U.S. Pat. No. 7,429,558 discloses azetidinium modified polymers and fabric treatment therefrom, that avoids stain fixing and dye adsorption.
U.S. Pat. No. 4,954,395 discloses a recording medium comprising an ink-transporting layer and ink-retaining layer. EP 0 947 350 discloses an ink jet recording material optionally comprising a cationic resin. US 2004/0263598 discloses a method for textile printing that includes a pre-treating that may include a fixing agent such as Danfix™ 723. US 2009/0191383 discloses a method of coloring textile substrates and a pretreatment bath. US2008/0024536 discloses an image forming apparatus and method along with cationic organic compounds.
The above references teach different ways to improve properties of images on various backgrounds. Some call for cationic polymers, some call for fabric softeners, some call for crosslinked particles, some recite titanium dioxide pigments while others use reactive dyes. They all seem to seek soft-feel images on textiles that have good color intensity, crisp well defined images, and good retention of color during mechanical washing of the textiles.